Question: $ { \left[\begin{array}{r}{2} \\ {1} \\ {-1}\end{array}\right]+\left[\begin{array}{r}{1} \\ {4} \\ {-2}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{r}{2}+{1} \\ {1}+{4} \\ {-1}+{-2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{3} \\ {5} \\ {-3}\end{array}\right]}$